Landing Strategy Adjustments Made by Female Gymnasts in Response to Drop Height and Mat Composition

1993 ◽  
Vol 9 (3) ◽  
pp. 173-190 ◽  
Author(s):  
Jill L. McNitt-Gray ◽  
Takashi Yokoi ◽  
Carl Millward
Keyword(s):  
Angular Position ◽  
Force Plate ◽  
Vertical Force ◽  
Drop Height ◽  
Time To Peak ◽  
Impact Peak ◽  
Force Time ◽  
Female Gymnasts ◽  
Landing Mat ◽  
Vertical Impact

In this study, drop height and landing mat composition were hypothesized to influence the landing strategies preferred by female gymnasts. Adjustments in strategy in response to changes in drop height and mat composition were identified by comparison of mechanical variables characterizing two-foot competition-style drop landings from three heights onto two different mats varying in composition (i.e., soft vs. stiff). Force-time characteristics of the landings were quantified (1000 Hz) by a force plate fully supporting the mat. Segment kinematics were recorded simultaneously with shuttered video (60 Hz). Significant differences (ANOVA; p < .05) in peak vertical force, landing phase time, time to peak vertical force, and lower extremity kinematics were found across drop heights. Only time to vertical impact peak and minimum knee angular position produced significant differences between the soft and stiff mats. These results indicate changes in drop height and mat composition may elicit changes in landing strategies of female gymnasts.

scholarly journals Concurrent Validity of a Portable Force Plate Using Vertical Jump Force–Time Characteristics

2018 ◽  
Vol 34 (5) ◽  
pp. 410-413 ◽  
Author(s):  
Jason Lake ◽  
Peter Mundy ◽  
Paul Comfort ◽  
John J. McMahon ◽  
Timothy J. Suchomel ◽  
...  
Keyword(s):  
Concurrent Validity ◽  
Vertical Jump ◽  
Reaction Force ◽  
Force Plate ◽  
Vertical Force ◽  
Jump Height ◽  
Strength Index ◽  
Limits Of Agreement ◽  
Force Time ◽  
Plate System

This study examined concurrent validity of countermovement vertical jump reactive strength index modified and force–time characteristics recorded using a 1-dimensional portable and laboratory force plate system. Twenty-eight men performed bilateral countermovement vertical jumps on 2 portable force plates placed on top of 2 in-ground force plates, both recording vertical ground reaction force at 1000 Hz. Time to takeoff; jump height; reactive strength index modified; and braking and propulsion impulse, mean net force, and duration were calculated from the vertical force from both force plate systems. Results from both systems were highly correlated (r ≥ .99). There were small (d < 0.12) but significant differences between their respective braking impulse, braking mean net force, propulsion impulse, and propulsion mean net force (P < .001). However, limits of agreement yielded a mean value of 1.7% relative to the laboratory force plate system (95% confidence limits, 0.9%–2.5%), indicating very good agreement across all of the dependent variables. The largest limits of agreement were for jump height (2.1%), time to takeoff (3.4%), and reactive strength index modified (3.8%). The portable force plate system provides a valid method of obtaining reactive strength measures, and several underpinning force–time variables, from unloaded countermovement vertical jump. Thus, practitioners can use both force plates interchangeably.

Modeling a Viscoelastic Gymnastics Landing Mat during Impact

2006 ◽  
Vol 22 (2) ◽  
pp. 103-111 ◽  
Author(s):  
Chris Mills ◽  
Matthew T.G. Pain ◽  
Maurice R. Yeadon
Keyword(s):  
High Speed ◽  
Force Plate ◽  
System Model ◽  
Video Cameras ◽  
Key Characteristics ◽  
Single Mass ◽  
Force Time ◽  
Mass Spring ◽  
The Impact ◽  
Landing Mat

Landing mats that can undergo a large amount of area deformation are now essential for the safe completion of landings in gymnastics. The objective of this study was to develop an analytical model of a landing mat that reproduces the key characteristics of the mat-ground force during impact with minimal simulation run time. A force plate and two high-speed video cameras were used to record the mat deformation during vertical drop testing of a 24-kg impactor. Four increasingly complex point mass spring-damper models, from a single mass spring-damper system, Model 1, to a 3-layer mass spring-damper system, Model 4, were constructed using Matlab to model the mat's behavior during impact. A fifth model composed of a 3-layer mass spring-damper system was developed using visual Nastran 4D. The results showed that Models 4 and 5 were able to match the loading phase of the impact with simulation times of less than 1 second for Model 4 and 28 seconds for Model 5. Both Models 4 and 5 successfully reproduced the key force-time characteristics of the mat-ground interface, such as peak forces, time of peak forces, interpeak minima and initial rates of loading, and could be incorporated into a gymnast-mat model.

Dynamic plantar pressure analysis. Comparing common insole materials

1992 ◽  
Vol 82 (10) ◽  
pp. 507-513 ◽  
Author(s):  
PB Sanfilippo ◽  
RM Stess ◽  
KM Moss
Keyword(s):  
Plantar Pressure ◽  
Human Subjects ◽  
Force Plate ◽  
Vertical Force ◽  
Time Integral ◽  
Pressure Time ◽  
Peak Plantar Pressure ◽  
Force Time ◽  
Dynamic Measures ◽  
Force Time Integral

A comparison of five commonly used insole materials (Spenco, PPT, Plastazote, Nickelplast, and Pelite) was made to evaluate their effectiveness in reducing plantar vertical pressures on human subjects during walking. With the use of the EMED-SF pedograph force plate system, dynamic measures of vertical force, force-time integral, peak plantar pressure, pressure-time integral, and area of foot-to-ground contact were compared with the force plate covered with each of the insole materials and without any interface material.

Force Plate Analysis of Dogs with Bilateral Hip Dysplasia Treated with a Unilateral Triple Pelvic Osteotomy: A Long-term Review of Cases

1998 ◽  
Vol 11 (02) ◽  
pp. 85-93 ◽  
Author(s):  
Joanne R. Cockshutt ◽  
H. Dobson ◽  
C. W. Miller ◽  
D. L. Holmberg ◽  
Connie L. Taves ◽  
...  
Keyword(s):  
Gait Analysis ◽  
Hip Dysplasia ◽  
Weight Bearing ◽  
Force Plate ◽  
Case Series ◽  
Pelvic Osteotomy ◽  
Vertical Force ◽  
Long Term Outcome ◽  
Case Series Study

SummaryA retrospective case series study was done to determine the long-term outcome of operations upon dogs treated for canine hip dysplasia by means of a triple pelvic osteotomy (TPO). Twentyfour dogs with bilateral hip dysplasia, that received a unilateral TPO between January 1988 and June 1995, were re-examined at the Ontario Veterinary College. The assessment included physical, orthopedic and lameness examinations, standard blood work, pelvic radiographs and force plate gait analysis. They were compared to bilaterally dysplastic dogs that had not been treated, and also to normal dogs. Force plate data analysis demonstrated a significant increase in peak vertical force (PVF) and mean vertical force over stance (MVF) in the limb that underwent surgical correction by means of a TPO, when compared to the unoperated hip. It was determined that performing a unilateral TPO on a young dysplastic dog resulted in greater forces and weight bearing being projected through the TPO corrected limb when compared to the unoperated limb.Dogs with bilateral hip dysplasia treated with a unilateral triple pelvic osteotomy (TPO) were assessed by force plate gait analysis, radiographs and orthopedic examination. There was a significant increase in hip Norberg angles over time, although degenerative changes did progress. Limbs that had been operated upon had significantly greater peak and mean ground reaction forces than limbs that had not received an operation.

Influence of Attached Masses on Impact Forces and Running Style in Heel-Toe Running

1987 ◽  
Vol 3 (3) ◽  
pp. 264-275 ◽  
Author(s):  
Alexander Bahlsen ◽  
Benno M. Nigg
Keyword(s):  
Body Mass ◽  
High Speed ◽  
Impact Force ◽  
Force Plate ◽  
The Body ◽  
Additional Mass ◽  
Impact Forces ◽  
Running Shoes ◽  
High Speed Film ◽  
Vertical Impact

Impact forces analysis in heel-toe running is often used to examine the reduction of impact forces for different running shoes and/or running techniques. Body mass is reported to be a dominant predictor of vertical impact force peaks. However, it is not evident whether this finding is only true for the real body mass or whether it is also true for additional masses attached to the body (e.g., running with additional weight or heavy shoes). The purpose of this study was to determine the effect of additional mass on vertical impact force peaks and running style. Nineteen subjects (9 males, 10 females) with a mean mass of 74.2 kg/56.2 kg (SD = 10.0 kg and 6.0 kg) volunteered to participate in this study. Additional masses were attached to the shoe (.05 and .1 kg), the tibia (.2, .4, .6 kg), and the hip (5.9 and 10.7 kg). Force plate measurements and high-speed film data were analyzed. In this study the vertical impact force peaks, Fzi, were not affected by additional masses, the vertical active force peaks, Fza, were only affected by additional masses greater than 6 kg, and the movement was only different in the knee angle at touchdown, ϵ0, for additional masses greater than .6 kg. The results of this study did not support findings reported earlier in the literature that body mass is a dominant predictor of external vertical impact force peaks.

Control of Rapidly Executed Forces to a Target

1987 ◽  
Vol 65 (3) ◽  
pp. 827-836
Author(s):  
Donald Siegel
Keyword(s):  
Visual Feedback ◽  
Predictor Variable ◽  
Peak Force ◽  
Important Predictor ◽  
Force Amplitude ◽  
Time Curve ◽  
Time To Peak ◽  
Hand Grip ◽  
Rapid Responses ◽  
Force Time

The purpose of the present study was to determine whether initial measures of impulse (i.e., area under the force-time curve) could be used to predict peak force (PF) in hand grip responses of 5- and 10-kg amplitude executed as rapidly as possible. 12 subjects performed 75 practice and 25 test contractions in each condition, with and without visual feedback. The time to peak (PT) for the 5-kg responses was 41 msec., while the 10-kg condition averaged 56 msec. Analyses demonstrated no effect for visual feedback. Correlational analyses of cumulative impulse sections from 5 msec., to PF within conditions showed that early measures of force within a response were not very good predictors of final force amplitude. Indeed, for both conditions upwards of 85% of a reponse needed to have occurred before 50% of PF variance could be predicted. Analyses across conditions demonstrated that 50% of PF variance could be predicted between 15 and 20 msec. PT was also an important predictor variable. By using PT along with cumulative impulse 50% of the variance in PF could be predicted prior to 10 msec., at 5 kg (25% of PT) and at about 15 msec., for 10 kg (27% of PT). Across conditions, 85% of the variance in PF was predictable by 5 msec. Such results suggest that either more refined response indices are needed in predicting response outcome or that even for very rapid responses some lower level “tuning” probably occurs after initiation.

Phase-Specific Force and Time Predictors of Standing Long Jump Distance

2021 ◽  
pp. 1-8
Author(s):  
John R. Harry ◽  
John Krzyszkowski ◽  
Luke D. Chowning ◽  
Kristof Kipp
Keyword(s):  
National Collegiate Athletic Association ◽  
Reaction Force ◽  
Vertical Force ◽  
Jump Height ◽  
Strength Index ◽  
Phase Duration ◽  
Standing Long Jump ◽  
Jump Distance ◽  
Long Jump ◽  
Force Time

This study sought to identify potential predictors of standing long jump (SLJ) performance using force–time strategy metrics within the unloading, eccentric yielding, eccentric braking, and concentric phases. Fifteen National Collegiate Athletic Association division 1 male soccer players (19 [1] y, 1.81 [0.94] m, 80.3 [22.4] kg) performed 3 maximum-effort SLJs, while 3-dimensional ground reaction force (GRF) data were obtained. Regularized regression models were used to investigate associations between force–time strategy metrics and 2 metrics of SLJ performance (ie, jump distance and modified reactive strength index). Jump height and eccentric yielding time were the only predictors of jump distance that also demonstrated large correlations to jump distance. Anterior–posterior unloading yank, average concentric vertical force, and concentric phase duration were the only predictors of modified reactive strength index that also demonstrated large correlations to modified reactive strength index. To maximize SLJ distance in high-level soccer athletes, human performance practitioners could design interventions to drive changes in strategy to increase jump height and decrease eccentric yielding time. To improve SLJ explosiveness, interventions to drive changes in unloading and concentric force application and decrease concentric time could be emphasized. Importantly, unique variable combinations can be targeted when training for SLJ distance and explosiveness adaptations.

scholarly journals Pushing up or pushing out—an initial investigation into horizontal- versus vertical-force training on swimming start performance: a pilot study

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10937
Author(s):  
Shiqi Thng ◽  
Simon Pearson ◽  
Justin W.L. Keogh
Keyword(s):  
Pilot Study ◽  
Resistance Training ◽  
Body Mass ◽  
Deliberate Practice ◽  
Training Programme ◽  
Concurrent Training ◽  
Training Intervention ◽  
Vertical Force ◽  
Squat Jump ◽  
Force Time

Background The block phase in the swimming start requires a quick reaction to the starting signal and a large take-off velocity that is primarily horizontal in direction. Due to the principle of specificity of training, there is a potential benefit of performing a greater proportion of horizontal force production exercises in a swimmers’ dry-land resistance training sessions. Therefore, the purpose of this pilot study was to provide an insight into the effects of a horizontal- (HF) vs vertical-force (VF) training intervention on swim start performance. Methods Eleven competitive swimmers (six males (age 20.9 ± 1.8 years, body mass 77.3 ± 9.7 kg, height 1.78 ± 0.05 m) and five females (age 21.4 ± 2.0 years, body mass 67.5 ± 7.4 kg, height 1.69 ± 0.05 m)) completed 2 weekly sessions of either a horizontal- or vertical-force focused resistance training programme for 8 weeks. Squat jump force-time characteristics and swim start kinetic and kinematic parameters were collected pre- and post-intervention. Results Across the study duration, the swimmers completed an average of nine swimming sessions per week with an average weekly swim volume of 45.5 ± 17.7 km (HF group) and 53 ± 20.0 km (VF group), but little practice of the swim start per week (n = 9). Within-group analyses indicated a significant increase in predicted one repetition maximum (1RM) hip thrust strength in the HF group, as well as significant increases in grab resultant peak force but reductions in resultant peak force of the block phase for the VF group. No significant between-group differences in predicted 1RM hip thrust and back squat strength, squat jump force-time and swim start performance measures were observed after 8 weeks of training. Significant correlations in the change scores of five block kinetic variables to time to 5 m were observed, whereby increased block kinetic outputs were associated with a reduced time to 5 m. This may be indicative of individual responses to the different training programmes. Discussion The results of this current study have been unable to determine whether a horizontal- or vertical-force training programme enhances swim start performance after an 8-week training intervention. Some reasons for the lack of within and between group effects may reflect the large volume of concurrent training and the relative lack of any deliberate practice of the swim start. Larger samples and longer training duration may be required to determine whether significant differences occur between these training approaches. Such research should also look to investigate how a reduction in the concurrent training loads and/or an increase in the deliberate practice of the swim start may influence the potential changes in swim start performance.

Variability of vertical ground reaction forces collected with one and two force plates in healthy dogs

2015 ◽  
Vol 28 (05) ◽  
pp. 318-322 ◽  
Author(s):  
M. Stejskal ◽  
B. T. Torres ◽  
G. S. Sandberg ◽  
J. A. Sapora ◽  
R. K. Dover ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Reaction Force ◽  
Force Plate ◽  
Plate Versus ◽  
Vertical Force ◽  
Vertical Ground Reaction Force ◽  
Coefficients Of Variation ◽  
Vertical Ground ◽  
Healthy Dogs ◽  
Collection Time

SummaryObjective: To compare peak vertical force (PVF) and vertical impulse (VI) data collected with one and two force plates during the same collection time period in healthy dogs at a trot.Animals: Seventeen healthy client-owned adult dogs.Methods: Vertical ground reaction force (GRF) data were collected in a crossover study design, with four sessions on two consecutive days, and then two weeks apart (days 1, 2, 15, and 16) using both one and two force plates collection methods. A repeated measures model analysis of variance (ANOVA) was used to test for differences in force plate PVF, VI, and average time per trial (ATT) between days, weeks, and systems (1 plate versus 2 plates). Coefficients of variation for PVF and VI were also calculated separately by forelimbs and hindlimbs, plates, day, and week.Results: The time required to obtain a valid trial was significantly longer using a single force plate when compared with two force plates. Comparing GRF data for all dogs, significant differences in PVF data were found between one and two force plates, however, these differences were diminutive in absolute magnitude, and of unknown clinical importance. Examination of the coefficients of variation for PVF and VI during the different collection periods yielded similar results.Conclusions: Use of two force plates decreased trial repetition and collection time. Vertical GRF data had a similar coefficient of variation with either one or two force plates collection techniques in healthy dogs.

scholarly journals Biomechanical assessment of various punching techniques

2020 ◽  
Author(s):  
Jiri Adamec ◽  
Peter Hofer ◽  
Stefan Pittner ◽  
Fabio Monticelli ◽  
Matthias Graw ◽  
...  
Keyword(s):  
High Speed ◽  
Vertical Wall ◽  
Force Plate ◽  
Physical Parameters ◽  
Time Curve ◽  
Biomechanical Assessment ◽  
Sports Science ◽  
General Terms ◽  
Force Time ◽  
The Impact

Abstract Punches without the use of instruments/objects are a common type of body violence and as such a frequent subject of medicolegal analyses. The assessment of the injuries occurred as well as of the potential of the assault to produce severe body harm is based on objective traces (especially the documented injuries of both parties involved) as well as the—often divergent—descriptions of the event. Quantitative data regarding the punching characteristics that could be used for the assessment are rare and originate mostly in sports science. The aim of this study was to provide physical data enabling/facilitating the assessment of various punching techniques. A total of 50 volunteers took part in our study (29 males and 21 females) and performed severe punches with the fist, with the small finger edge of the hand (karate chop), and with the open hand with both the dominant and the non-dominant hands in randomized order. The strikes were performed on a boxing pad attached to a KISTLER force plate (sampling frequency 10,000 Hz) mounted on a vertical wall. The punching velocity was defined as the hand velocity over the last 10 cm prior to the contact to the pad and ascertained by using a high-speed camera (2000 Hz). Apart from the strike velocity, the maximum force, the impulse (the integral of the force-time curve), the impact duration, and the effective mass of the punch (the ratio between the impulse and the strike velocity) were measured/calculated. The results show a various degree of dependence of the physical parameters of the strikes on the punching technique, gender, hand used, body weight, and other factors. On the other hand, a high degree of variability was observed that is likely attributable to individual punching capabilities. In a follow-up study, we plan to compare the “ordinary” persons with highly trained (boxers etc.) individuals. Even though the results must be interpreted with great caution and a direct transfer of the quantitative parameters to real-world situations is in general terms not possible, the study offers valuable insights and a solid basis for a qualified forensic medical/biomechanical assessment.

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